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Forall
Summary
Code reviews catch logic errors late, tests miss edge cases, and formal correctness stays confined to academic papers — Forall exists for the gap between 'the tests pass' and 'the code is provably correct.'
Forall is an Apache-2.0 CLI agent from Astrio that generates spec-driven code alongside machine-checkable proofs, running entirely in your terminal or wiring into Cursor, Claude Code, or Codex via MCP. You describe what the code must do; the agent produces both the implementation and a formal proof you can verify independently. The verification step is not optional decoration — it runs against the spec, so a failing proof surfaces a real logical flaw before the code ships. The docs describe Rust, TypeScript, and Java as the supported targets, which covers a specific but meaningful slice of production codebases. Teams outside those languages hit a hard wall.
Bottom line: Pick Forall when you are building safety-critical Rust or TypeScript logic and need proof, not confidence — but if your stack is Python, Go, or anything outside the supported trio, the verification layer does not exist yet.
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Pros
Sign in to edit- Generates machine-checkable proofs alongside code, so correctness is verifiable by a tool rather than trusted on faith — eliminating the class of bugs that pass all tests but violate the spec.
- Apache-2.0 license with a self-hosted CLI path, which means the proof pipeline runs on your infrastructure without sending proprietary specs to a third-party service.
- MCP integration drops the agent directly into Cursor, Claude Code, or Codex via a config block, so teams avoid a context switch to a separate tool when they want verification mid-session.
- Spec-driven generation disciplines the coding workflow upfront, which means the spec ambiguities that normally surface in code review get resolved before the first line is written.
- Agentic execution runs specs-to-proof autonomously in the terminal, so verification does not require manual orchestration between separate tools for generation and checking.
Cons
Sign in to edit- Language support is limited to Rust, TypeScript, and Java — a Python, Go, or C++ team gets zero proof generation, and the vendor page describes no roadmap for expansion, leaving those teams with no path forward except switching to a different verification approach entirely.
- Spec-driven development requires writing formal specifications before generating code; teams without prior exposure to this discipline spend non-trivial time learning to write specs that are precise enough for the proof system to use, at which point the productivity argument against traditional TDD weakens.
- Teams whose correctness requirements are satisfied by property-based testing tools — like QuickCheck for Haskell or Hypothesis for Python — have an established, language-native alternative that does not require adopting a new agent layer and may switch there rather than retrofit Forall into an incompatible stack.
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About
- Platforms
- CLI, terminal, MCP clients
- API Available
- Yes
- Self-Hosted
- Yes
- Last Updated
- 2026-07-18T08:15:50.727Z
Best For
Who it's for
- Developers needing machine-checkable proofs
- Rust, TypeScript, or Java projects
- Spec-driven coding with verification
What it does well
- Generating verified code from specifications in a terminal
- Adding formal proof verification to existing coding workflows
- Using in Cursor, Claude Code, or Codex via MCP
Integrations
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Frequently Asked Questions
- Is Forall free?
- Forall has a permanent free tier alongside paid upgrades. You can keep using a baseline version indefinitely without paying.
- Is Forall open source?
- Yes. Forall is open source.
- Does Forall have an API?
- Yes. Forall exposes a developer API. See the official documentation at https://github.com/astrio-labs/forall for details.
- Can I self-host Forall?
- Yes. Forall supports self-hosting on your own infrastructure.
- When was Forall released?
- Forall was first released in 2026.
- What platforms does Forall support?
- Forall is available on: CLI, terminal, MCP clients.
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Curated lists that include this category
Most confidence in code is probabilistic: tests pass, coverage looks good, the reviewer approved it. Forall takes a different position. The agent reads a specification, generates code against it, and produces a machine-checkable proof that the implementation satisfies the spec — not a lint warning, not a type hint, a formal mathematical proof. The workflow runs from the terminal via a CLI installed with a single curl command, or through an MCP config that plugs the same agent into editors like Cursor or Claude Code, giving teams the verification step inside the tool they already use.
The differentiating feature is the proof artifact itself. Most AI coding agents produce code you then trust or test. Forall produces code paired with a verifiable proof — meaning the correctness claim is checkable by a separate tool, not just by re-running the agent. The vendor describes this as spec-driven development with machine-checkable outputs, which shifts the debugging question from ‘did the tests catch it’ to ‘does the proof hold.’
Forall fits tightest into workflows where correctness is non-negotiable and the stack is Rust, TypeScript, or Java — financial logic, protocol implementations, security-critical parsing. It fits poorly when the project language sits outside those three, when the team has no existing culture around formal specifications, or when the spec-writing overhead outweighs the verification benefit for the task at hand. Teams doing rapid prototyping will find the proof generation step adds friction that serves no purpose until the code stabilizes.
The tool ships under Apache-2.0, self-hosts via the CLI, and exposes a hosted verification path through a FORALL_API_KEY. The MCP integration means the agent surfaces inside Cursor, Claude Code, or Codex without a separate context switch. The GitHub repo sits at astrio-labs/forall and includes an install.sh, examples directory, and a skills directory — the docs describe the agent behavior as autonomous, running specs-to-proof without manual step-by-step prompting.